1. Field of the Invention
The invention relates to a facet mirror comprising a number of mirror facets, wherein the mirror facets are provided with reflecting surfaces and a bearing device in each case, to a system for adjusting the mirror facets of a facet mirror, and to the use of such a facet mirror in microlithography.
2. Description of the Related Art
Reference is made to EP 0 726 479 A2, EP 0 901 992 A1, GB 2 255 195 A, DE 23 637 65, Patent Abstract of Japan 2000 167683A, RO 101091B, U.S. Pat. No. 6,154,302 A, U.S. Pat. No. 6,227,673 B U.S. Pat. No. 1, 4,195,913 and U.S. Pat. No. 4,740,276 in relation to the prior art.
It is scarcely possible in the case of the known facet mirrors to realize the accuracies required for the mirror facets during adjustment, which are required for the preferred application of the above-named invention in an objective for semiconductor lithography, in particular for use under radiation in the extreme ultraviolet region. Moreover, during an adjustment of the mirror facets it is possible to access the individual mirror facets only from the side of their reflecting surface, and so aligning the individual mirrors under illumination is relatively complicated and difficult.